Fertility in horses encompasses the physiological processes and factors influencing reproductive success in equine species. It involves the study of reproductive anatomy, endocrinology, and behavior, as well as the management practices that affect breeding outcomes. Key aspects include the estrous cycle, conception rates, and factors impacting stallion and mare fertility. Reproductive technologies such as artificial insemination, embryo transfer, and hormonal therapies are also explored to enhance breeding efficiency. This page compiles peer-reviewed research studies and scholarly articles that examine the biological mechanisms, management strategies, and technological advancements related to equine fertility.
Malmgren L, Andresen O, Dalin AM.The aim of this study was to investigate the effect of gonadotrophin-releasing hormone (GnRH) immunisation on mature stallions that had been used for breeding. Four Standardbred stallions were used in the study: 3 experimental animals and 1 control animal. Semen was collected regularly, i.e. twice/week, during the 4 months prior to the experimental period. The stallions were immunised against GnRH with a GnRH-BSA conjugate. Equimune was used as the adjuvant. The stallions were immunised on 5 occasions, 4 at 2 week intervals, and the fifth 4 weeks after the fourth. Blood samples were taken once...
Blottner S, Warnke C, Tuchscherer A, Heinen V, Torner H.The study compared quality and freezability of stallion semen during breeding and non-breeding seasons. Ejaculates were collected twice per week from four stallions during May (n = 24) and December (n = 24). The semen was mixed with skim milk extender, centrifuged and resuspended in fresh extender. Aliquots of this sperm suspension were separated from extender and diluted in TALP medium for sperm evaluation or with cryoextender (type "Gent" or a combination of Triladyl and skim milk). Samples of 0.5ml were cryopreserved in straws using a programmed freezer. Parameters of sperm quality were eva...
Carnevale EM, Squires EL, Maclellan LJ, Alvarenga MA, Scott TJ.In some mares with lesions of the reproductive tract, embryo collection and survival rates are low, or collection of embryos is not feasible. For these mares, oocyte transfer has been proposed as a method to induce pregnancies. In this report, a method for oocyte transfer in mares and results of oocyte transfer performed over 2 breeding seasons, using mares with long histories of subfertility and various reproductive lesions, are described. Human chorionic gonadotropin or an implant containing a gonadotropin-releasing hormone analog was used to initiate follicular and oocyte maturation. Oocyte...
Gradil CM, Ball BA.Pentoxifylline was evaluated as a method to increase motility of cryopreserved equine spermatozoa. In a preliminary experiment, pentoxifylline (3.5 mM or 7.0 mM) was added to extended semen that was chilled to 4 degrees C. Motility was evaluated at 8-h intervals for 48 h. The addition of 3.5 or 7.0 mM pentoxifylline appeared to increase the motility of chilled spermatozoa compared to controls. Based on these results, similar concentrations of pentoxifylline were added to semen either before or after cryopreservation. The addition of pentoxifylline (3.5 or 7.0 mM) to semen before cryopreservati...
Neild DM, Chaves MG, Flores M, Miragaya MH, Gonzalez E, Agüero A.The hypo-osmotic test has been used successfully on equine semen and was considered to be a simple and accessible method which could be a useful addition to routine equine semen analysis. It was therefore of interest to determine whether the hypo-osmotic test is significantly correlated to proposed criteria of fertility. The stallions were divided into two groups on the basis of threshold levels of fertility. A significant difference (P<0.05) was found between the two groups for the following parameters: progressive motility, morphologically normal spermatozoa, percentage of swelling with t...
Stradaioli G, Sylla L, Zelli R, Verini Supplizi A, Chiodi P, Arduini A, Monaci M.The reproductive characteristics and seminal carnitine and acetylcarnitine content as well as carnitine acetyltransferase activity of young Maremmano stallions (n=25) are reported. The stallions were subjected to semen collection in November and January; in each trial two ejaculates were collected 1h apart. The total motile morphologically normal spermatozoa (TMMNS) and the progressively motile spermatozoa at collection and during storage at +4 degrees C were evaluated. Seminal L-carnitine (LC), acetylcarnitine (AC), pyruvate and lactate were measured using spectrophotometric methods, whereas ...
McCue PM, Hendrickson DA, Hess MB.To develop a technique for laparoscopic tubal (oviductal) ligation and to evaluate pregnancy rates for mares that ovulated ipsilateral or contralateral to the ligated oviduct. Methods: Randomized prospective clinical trial comparing pregnancy rates after unilateral laparoscopic tubal ligation. Methods: Twelve mares of light horse breeds. Methods: One oviduct in each of 6 mares was surgically ligated with a laparoscopic technique; 6 other mares served as nonligated controls. Mares with unilateral tubal ligations (UTL) were inseminated with 500 million progressively motile sperm during 1 cycle w...
Carnevale EM, Maclellan LJ, Coutinho da Silva MA, Scott TJ, Squires EL.This study was designed to test 3 approaches for insemination and transfer of oocytes to recipient mares. Oocytes were recovered transvaginally from naturally cycling donor mares 24 to 26 h after an intravenous injection of 2500 IU of hCG when follicles reached 35 mm in diameter. Multiple oocytes (1 to 4) were transferred surgically into the oviducts of 4 or 5 recipient mares per group. Three groups of transfers were compared: 1) transfer of oocytes cultured in vitro for 12 to 14 h postcollection with insemination of the recipient 2 h postsurgery; 2) transfer of oocytes into the oviduct within...
Vidament M, Ecot P, Noue P, Bourgeois C, Magistrini M, Palmer E.The aims of this study were to evaluate the effects of cooling rate to 4 degrees C and temperature at the time of centrifugation/glycerol-addition (freezing extender: INRA82 + 2% egg yolk + 2.5% glycerol) on postcentrifugation recovery rate, post-thaw motility and per-cycle fertility. When centrifugation/glycerol-addition was performed at 4 degrees C (14 ejaculates), a moderate cooling rate (37 degrees C to 4 degrees C in I h) resulted in higher post-thaw motility (45%) than when using a slow cooling rate (37 degrees C to 4 degrees C in 4 h) (39%; P<0.05). When centrifugation/glycerol-addit...
Carnevale EM, Ramirez RJ, Squires EL, Alvarenga MA, Vanderwall DK, McCue PM.In the present study, 638 embryo transfers conducted over 3 yr were retrospectively examined to determine which factors (recipient, embryo and transfer) significantly influenced pregnancy and embryo loss rates and to determine how rates could be improved. On Day 7 or 8 after ovulation, embryos (fresh or cooled/transported) were transferred by surgical or nonsurgical techniques into recipients ovulating from 5 to 9 d before transfer. At 12 and 50 d of gestation (Day 0 = day of ovulation), pregnancy rates were 65.7% (419 of 638) and 55.5% (354 of 638). Pregnancy rates on Day 50 were significantl...
Alvarenga MA, Landim-Alvarenga FC, Moreira RM, Cesarino MM.The present experiments aimed to examine the substitution of glycerol (G) by ethylene glycol (E) as a cryoprotective agent for stallion spermatozoa. Two different ethylene glycol concentrations (5% and 10%) and also the association of glycerol (2%) and ethylene glycol (3%) (E/G) were studied (Experiment 1). In Experiment 2, two packing systems (0.5 x 4.0 ml) were evaluated using both cryoprotectors. In both experiments, the sperm membrane integrity after freezing was evaluated using transmission electron microscopy. The mean post-thaw motility was 34.25, 36.5, 29.25 and 34.75% for G5%, E5%, E1...
Retamal C, Urzúa J, Lorca C, López ML, Alves EW.The present paper reports modifications in the electrophoretic and cytochemical characteristics of mature and immature stallion spermatozoa. Some sperm surface glycoproteins (36, 32, 29, 21, 20, 18 kDa) detected in cauda epididymidis spermatozoa, were either absent or present in a very low relative concentration in immature sperm cells. A major 14 kDa protein band, observed in sperm extracts obtained from ductus efferentes, progressively decreased along the epididymal ductus. The nature and distribution of carbohydrate residues on the sperm membrane, during epididymal maturation, was also stud...
Reilas T, Huhtinen M, Oksanen M, Katila T.The aim of the study was to determine whether neutrophil numbers (PMN), trypsin-inhibitor capacity (TIC), lysozyme, N-acetyl-beta-D-glucosaminidase (NAGase), beta-glucuronidase (B-Gase), total protein, and plasmin in uterine lavage fluid of postpartum (p.p.) mares, either at the time of foal heat insemination or around the time of arrival of the embryo in the uterus, could be used in predicting conception. Fifteen mares were inseminated within 13 h after the first p.p. ovulation. Uterine lavage fluids were successfully collected from 9 out of 12 mares before insemination and from all 15 mares ...
Davies Morel MC, Gunnarsson V.Very limited information is available on the breeding performance of Icelandic stallions, let alone the effect that management practices may have had on such performance. As an extensively kept, largely genetically isolated breed of horse it provides a good model for the study of factors that affect reproductive performance without the additional complication of selective breeding, infectious infertility and breed effect. A survey was conducted using 27 Icelandic stallions covering 1590 mares within the normal Icelandic breeding system (May to September). During the season, stallions cover mar...
Brinsko SP, Crockett EC, Squires EL.The objective of this study was to determine if centrifugation and partial removal of seminal plasma would improve spermatozoal motility in semen from stallions whose whole ejaculates have poor tolerance to cooling and storage. Stallions were divided into two groups (n = 5/group) based on the ability of their extended semen to maintain spermatozoal motility after cooling and storage. Group 1 stallions ("good coolers") produced semen in which progressive spermatozoal motility after 24 h of cooling and storage was reduced by < or = 30% of progressive motility prior to storage. Group 2 stallions ...
Woods J, Rigby S, Brinsko S, Stephens R, Varner D, Blanchard T.Two trials were conducted to investigate the effects of intrauterine infusion of PGE2 and uterine horn insemination on pregnancy rates in mares achieved by breeding with a suboptimal number of normal spermatozoa. Estrus was synchronized and mares were teased daily with a stallion to detect estrus. Mares in estrus were examined by transrectal palpation and ultrasonography to monitor follicular status. On the first day a 35-mm diameter follicle was present, hCG (1500 IU, iv) was administered and the mares were bred the next day. Mares (Trial 1, n = 34; Trial 2, n = 28) were inseminated with 25 m...
Gravance CG, Garner DL, Baumber J, Ball BA.The fluorescent carbocyanine dye, JC-1, labels mitochondria with high membrane potential orange and mitochondria with low membrane potential green. Evaluation of mitochondrial membrane potential with JC-1 has been used in a variety of cell types, including bull spermatozoa; however, JC-1 staining has not yet been reported for equine spermatozoa. The aim of this study was to apply JC-1 staining and assessment by flow cytometry or a fluorescence microplate reader for evaluation of mitochondrial function of equine spermatozoa. Six ejaculates from four stallions were collected and centrifuged thro...
Eagle RC, Tortonese DJ.Little is known about the neuroendocrine control of fertility in the horse. In this species, unusual features characterize the normal estrous cycle such as a prolonged preovulatory LH surge during the follicular phase and a distinctive FSH surge during the midluteal phase. This study investigated the distribution and hormonal identity of gonadotrophs in the pars distalis (PD) and pars tuberalis (PT) of the equine pituitary gland as possible morphological bases for the referred unusual endocrine characteristics. In addition, the proportion of gonadotrophs in relation to other pituitary cell typ...
Bergman HJ, de Kruif A, van Dessel S.In this article different possible treatments for problem mares are discussed. The therapeutic possibilities vary and can be classified into anatomical correction, anti-infectious therapy, and treatment to enhance the uterine defence mechanisms. Anatomical correction and treatment with antibiotics are valuable therapies and have been used for many years. In recent years, stimulation of the mechanical defence mechanism of the uterus, by flushing it with physiological solution combined with parenteral oxytocin, has been shown to increase the chance of getting problem mares in foal.
Brinsko SP, Rowan KR, Varner DD, Blanchard TL.This study was conducted to compare the cooling rates and storage temperatures within equine semen transport containers exposed to different ambient temperatures, and to evaluate the ability of these containers to preserve spermatozoal motility following 24 h of storage under these conditions. In Experiment 1, nonfat dried milk solids, glucose, sucrose, equine semen extender was divided into seven 40-mL aliquots and loaded into seven different semen transport containers: Equitainer I, Equitainer II, Equitainer III, ExpectaFoal, Bio-Flite, Lane STS, and Equine Express. After containers were loa...
Bergman HJ, de Kruif A, van Dessel S.A review is given of treatment for 'problem' mares that do not become pregnant. To determine the best therapy, it is necessary to understand the defence mechanisms of the uterus and the pathogenesis of not getting in foal. A thorough clinical examination is absolutely necessary to come to a correct diagnosis. This examination will be explained in a practical way. In the second article the different therapies for treating problem mares are discussed. The therapeutic possibilities vary widely. They can be classified in: anatomical corrections, anti-infectious therapy, and treatment to enhance th...
Retamal C, Urzúa J, Alves EW, López ML.It has been suggested that proteins produced in specific regions of the epididymis, mostly androgen dependent glycoproteins, are involved in the sperm maturation process. In the present work, the glycoconjugated distribution pattern and the electrophoretic characteristics of the stallion epididymal proteins were examined using lectin probes. The identification in the luminal fluid of some new proteins, probably synthesized and secreted by the epididymis, is an important initial step to investigate their interaction with the stallion sperm membrane. The binding of FITC-lectins (ConA, WGA, LPA, ...
Li X, Morris LH, Allen WR.The effects of four reagents on the activation and subsequent fertilization of equine oocytes, and the development of these after intracytoplasmic sperm injection, were investigated. Cumulus-oocyte complexes collected from equine ovaries obtained from an abattoir were matured in vitro for 40-44 h in TCM199 medium before being injected, when in metaphase II, with an immobilized stallion spermatozoon. The cumulus-oocyte complexes were then subjected to one of five activation treatments: (a) 10 micromol ionomycin l(-1) for 10 min; (b) 7% (v/v) ethanol for 10 min; (c) 100 micromol thimerosal l(-1)...
Lagares MA, Petzoldt R, Sieme H, Klug E.The swelling of cells in a hypo-osmotic medium has been described as an important criterion for assessing the functional integrity of the sperm plasma membrane. The resistance of equine spermatozoa to osmolarity changes was studied by extending 98 semen samples collected from nine stallions in media at five osmolarities (300, 200, 150, 100, and 50 mOsmol l(-1)). The response of the cells was measured by the spermatocrit technique and eosin staining. Spermatocrit determines the increase on spermatozoal volume under hypo-osmotic conditions, a sign of functional integrity of sperm plasma membrane...
Nagy P, Guillaume D, Daels P.In this review, we have attempted to summarize, based on recent data obtained in our laboratory and elsewhere, our current understanding of the regulatory mechanisms of seasonality and discuss the implications with regard to treatment strategies to advance the onset of cyclic reproductive activity in the early spring.
Watson ED.Post-breeding endometritis is a major cause of subfertility in the mare. Endometritis is a normal event in the immediate period after mating, but the presence of ultransonographically visible uterine fluid more than 12 h later is thought to be evidence of uterine pathology. In mares that are free of venerally transmitted endometritis, treatment is aimed at removing the intraluminal fluid. If the endometritis persists past day 5, when the embryo enters the uterine lumen, the cytotoxic environment will not be compatible with pregnancy. Reproductive anatomy, defective myometrial contractility, lo...
McDonnell SM.Based on observational studies comparing social organization and reproductive behavior of equids breeding under feral, semi-feral, and domestic conditions, a series of comparisons and findings on reproductive physiology and behavior are presented. Simple changes in management and handling of mares and stallions that can improve reproductive efficiency and fertility or that can overcome specific breeding problems are discussed.
Varner DD, Blanchard TL, Brinsko SP, Love CC, Taylor TS, Johnson L.Numerous techniques may be used for evaluation of the different reproductive disorders of the stallion. Approaches may vary from real-time ultrasonography and biopsy for evaluating testicular tumors to use of special assays for evaluating sperm or plasma for presence of antisperm antibodies. This communication addresses techniques used to evaluate five relatively uncommon, but perplexing, disorders of breeding stallions: (1) seminal vesiculitis, (2) hemospermia associated with idiopathic urethral defects, (3) acrosomal dysfunction, (4) abnormal spermatozoal chromatin, and (5) azoospermia.
Buchanan BR, Seidel GE, McCue PM, Schenk JL, Herickhoff LA, Squires EL.Two experiments were conducted to determine pregnancy rates in mares inseminated 1) with 5, 25 and 500 x 10(6) progressively motile spermatozoa (pms), or 2) with 25 x 10(6) sex-sorted cells. In Experiment 1, mares were assigned to 1 of 3 treatments: Group 1 (n=20) was inseminated into the uterine body with 500 x 10(6) pms. Group 2 (n=21) and Group 3 (n=20) were inseminated into the tip of the uterine horn ipsilateral to the preovulatory follicle with 25 and 5 x 10(6) pms, respectively. Mares in all 3 groups were inseminated either 40 (n=32) or 34 h (n=29) after GnRH administration. More mares ...
Irvine CH, Alexander SL, McKinnon AO.The aim was to define precisely the FSH secretion pattern in mares during the two ovulatory cycles before, and for 24 days after, the last ovulation of the season and to compare this with the profiles of other reproductive hormones and follicular growth to identify changes which may lead to the termination of follicular cycles. Jugular blood was collected every 6 h from ten light horse mares for 6 weeks in autumn. Samples were assayed for FSH, LH, prolactin, inhibin, oestrone conjugates and progesterone. Luteolysis occurred earlier and periovulatory oestrone, but not inhibin, concentrations we...
Del Campo MR, Donoso X, Parrish JJ, Ginther OJ.Equine oocytes (n = 537) were collected from slaughterhouse ovaries (n = 118 mares) by scraping the internal follicular wall. Preculture record was made of the appearance of oocyte investments (no cumulus, corona radiata only, compact cumulus, expanded cumulus), appearance of cytoplasm (homogeneous, condensed heterogeneous/fragmented), and nuclear maturation stages (germinal vesicle, germinal-vesicle breakdown, metaphase I, metaphase II, degenerated). There was no difference between follicles > 30 mm and follicles < or = 30 mm in the preculture frequency distribution among the 5 nuclear stages...
Choi YH, Chung YG, Seidel GE, Squires EL.The objective was to compare culture media for in vitro maturation of equine oocytes and for in vitro culture of zygotes produced from IVF of partially zona-removed oocytes. Cumulus-oocyte complexes from slaughterhouse-derived ovaries were washed in m-Dulbecco's PBS and cultured in TCM-199, F10-DMEM or c-F10-DMEM (50% F10-DMEM + 50% F10-DMEM conditioned medium from culture of an equine trophoblast monolayer for 3 or 4 days). All media included FSH, LH, E2, and 10% FCS. After 28 to 30 h maturation, cumulus expansion was scored from 0 (no expansion) to 4 (fully expanded). Oocytes with a 1st pola...
Kareskoski M, Vakkamäki J, Laukkanen K, Palviainen M, Johannisson A, Katila T.Matrix metalloproteinase (MMP)-2 and MMP-9 are gelatinases that take part in several reproductive processes. The aim of this study was to measure levels of MMP-2 and MMP-9 in fractionated stallion ejaculates, and to evaluate the association between these components and semen quality, and sperm longevity during cooled storage. Semen quality were assessed separately for sperm-rich fractions (HIGH), sperm-poor fractions (LOW), and whole ejaculate samples (WE) from 33 stallions. After cooled storage with SP either present or removed, sperm motility and DFI were determined. The relative activity of...
Runcan EE, Pozor MA, Zambrano GL, Benson S, Macpherson ML.The acrosome is a highly specialised region of the spermatozoon that is essential for fertilisation. Defects or dysfunction of this structure have been associated with fertility problems in man and various domestic species including stallions. Current methods of evaluating the acrosome of stallion spermatozoa are time consuming and require specialised equipment, which is cost prohibitive to the average practitioner. Objective: To evaluate 2 conventional stains (Dip Quick and Spermac) and determine their usefulness in assessing acrosome integrity in stallions as compared with specific acrosomal...
Arthur GH.The effect of intrauterine saline on reproductive function was studied by infusion of mares in anoestrus, dioestrus, oestrus and prolonged dioestrus. Anoestrous mares were unaffected except near the beginning and end of the breeding season when anovulatory heats were induced. Dioestrous mares infused between Days 5 and 9 returned to heat an average of 3-8 days earlier than expected, and infusions during dioestrus were followed by ovulatory heats of normal fertility. Three mares in prolonged dioestrus showed ovulatory heats within 3 to 9 days of infusion. Infusions during oestrus had no appreci...
Chevalier F, Palmer E.Ultrasonic echography in the mare allows pregnancy diagnosis as early as Day 14 after ovulation. In the 1980 and 1981 breeding seasons, a total of 7438 examinations of 4688 mares were performed on several farms with the same apparatus. The accuracy of positive pregnancy diagnosis was estimated to be greater than 95% and of non-pregnancy diagnosis greater than 84%. When abnormal pictures of vesicles are found, it has to be decided whether it is a conceptus or a cystic structure. Most small vesicles do not develop, whereas large ones, deformed shapes, presence of some echoes, or a division insid...
Sales FABM, Azevedo MV, Souza NM, Ferreira-Silva JC, Chaves MS, Junior VR, Rocha JM, Dos Santos Filho JP, Freitas VJF, Oliveira MAL.The aim of this study was to evaluate the correlation between the corpus luteum vascularization with the concentration of progesterone and the fertility of embryo recipient mares. Mangalarga Marchador mares (n = 33) were distributed into groups according to the days (D) after ovulation, as follows: D3 (n = 8), D4 (n = 8), D5 (n = 9), and D6 (n = 8). The evaluations of the corpus luteum, endometrium, and blood collection to quantify the progesterone concentration were carried out on D3, D4, D5, and D6. Among the parameters evaluated, only progesterone concentration on D6 differed from the other...
Kirkpatrick JF, Liu IM, Turner JW, Bernoco M.Twenty-six free-roaming feral mares were immunized against porcine zonae pellucidae (PZP) between February and May, 1988. Eight sexually mature mares received 2 inoculations 2 weeks apart, and 18 mares received 3 inoculations at intervals of 2 and 4 weeks. Analysis of urinary oestrone conjugates (E1C) and non-specific progesterone metabolites (iPdG) in samples collected in October, 1988, revealed that none of the 18 mares that received 3 and only 1 of the 6 mares that received two inoculations were pregnant, whereas 3 of 6 sham-injected control mares and 5 of 11 untreated mares were pregnant. ...
Hyland JH, Wright PJ, Clarke IJ, Carson RS, Langsford DA, Jeffcott LB.In Exp. 1, 30 Standardbred mares in deep seasonal anoestrus were divided into 3 equal groups and treated with 0, 50 (G50) or 100 (G100) ng GnRH kg-1h-1 for 28 days via osmotic minipumps. Ovulation occurred in 0/10, 3/10 and 7/10 mares respectively (P less than 0.05). Plasma GnRH profiles (Days -6, 0, 2, 6, 12, 20, 28 and 34 relative to pump insertion) were dose-dependent (P less than 0.01) and peaked on Day 12 of infusion. Mean daily plasma LH concentrations were biphasic in treated mares that ovulated, with LH peaks occurring around Day 6 and Days 16-20. By contrast, in treated mares that did...
Tortonese DJ, Gregory SJ, Eagle RC, Sneddon CL, Young CL, Townsend J.The intrahypophysial mechanisms involved in the control of gonadotrophin secretion remain unclear. In the horse, a divergent pattern of gonadotrophins is observed at different stages of the reproductive cycle in response to a single secretagogue (gonadotrophin-releasing hormone), and dramatic changes in fertility take place throughout the year in response to photoperiod. This species thus provides a useful model to investigate the regulation of fertility directly at the level of the hypophysis. A series of studies were undertaken to examine the cytological arrangements and heterogeneity of gon...
Einarsson S, Dalin AM, Lundeheim N.The present study investigated daily sperm output and sperm morphology of fresh semen in eight Swedish Warmblood stallions aged 5-8 years. They were used for artificial insemination, and their fertility during the breeding season of semen collection exceeded 60% per cycle. One ejaculate of semen was collected daily for 10 consecutive days from each stallion. The gel-free volume was measured, and the sperm concentration was assessed with a Bürker chamber. The volume of gel-free fraction was multiplied by the sperm concentration to give the total number of spermatozoa (TSN). Sperm morphology wa...
Allen WR, Sanderson MW, Greenwood RE, Ellis DR, Crowhurst JS, Simpson DJ, Rossdale PD.A total of 18 experimental pony and 136 commercial maiden, barren and foaling Thoroughbred mares in seasonal or lactation-related anoestrus were injected subcutaneously with 1 or 2 slow-release D,L-lactide-glycolide co-polymer implants impregnated with 0.9 or 1.8 mg of the potent GnRH analogue, ICI 118 630, to give a daily release of, respectively, 30 or 60 micrograms analogue for 28 days; 32 of the Thoroughbred mares were also given a daily oral dose of 27.5 mg allyl trenbolone for 5 days after injection of the implant. Thirteen pony (76%) and 120 Thoroughbred (88%) mares ovulated 3-18 days a...
Serafini R, Varner DD, Bissett W, Blanchard TL, Teague SR, Love CC.The effect of flash-freezing storage temperature on stallion sperm DNA has not been evaluated. Commonly, sperm are flash-frozen at various temperatures to preserve sperm DNA prior to analysis. It is unclear whether the temperature at which sperm are frozen and stored may affect the results of DNA assays. In this study, the neutral comet assay was used to evaluate the effect of flash-freezing storage temperature (freezer [-60 °C], dry ice [-78.5 °C], liquid nitrogen [-196 °C]) compared to fresh sperm DNA structure. In addition, intra- and inter-assay and intra- and inter-stallion variabil...
Pace MM, Sullivan JJ.Fertilization rate was highest in mares inseminated with frozen semen within 12 hr of ovulation. Foaling rate was improved (P less than 0-05) by increasing the number of motile spermatozoa inseminated from 40 X 10(6) to 80 X 10(6) but was not further improved by increasing the number to 160 X 10(6) or by increasing the frequency of insemination from once to twice daily. The fertilizing capacity of spermatozoa frozen in one of the hydrogen ion extenders studied was dependent upon relative osmotic pressure and method of freezing (ampoules or pellets). Adjusting glycerol concentration from 7% to ...
Malinowski K, Johnson AL, Scanes CG.The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian cha...
Al-Jaru A, Goodwin W, Skidmore J, Raudsepp T, Khazanehdari K.Chromosome configurations and chiasma frequency during the metaphase I stage of spermatogenesis in the male horse are characterized in this work. The genome-wide frequency and distribution of chiasmata was detected as 49.45 ± 2.07 for 14 fertile stallions. All X and Y chromosomes shared a single chiasma at their pseudoautosomal region, while 1-4 chiasmata were observed in autosomal chromosomes. The chiasma frequency and distribution were further studied for 8 different bivalents identified by FISH in 5 fertile stallions. Genetic length was calculated from chiasmata data for the whole genome a...
Ginther OJ, Domingues RR, Dangudubiyyam SV, Araujo ER.Diameter deviation or follicle selection during a follicular wave begins with continuous growth rate of F1 (dominant or selected follicle; DF) and decreasing growth rate of F2 (largest subordinate). Intraovarian patterns based on presence or absence of the DF and CL are DF-CL, DF, CL, and devoid (neither DF nor CL). The DF and CL relationships in a pair of ovaries are ipsilateral (DF-CL pattern and devoid pattern) and contralateral (DF pattern and CL pattern). The effects of patterns and relationships on F1, F2, and FSH during deviation were determined in 21 mares. Diameters of F1 and F2 at ex...
Mari G, Bucci D, Love CC, Mislei B, Rizzato G, Giaretta E, Merlo B, Spinaci M.The aim of this study was to compare the effect of presorting centrifugation (cushioned [CC] or single-layer colloid [SLC]), with simple dilution (SD), on the quality of sex-sorted stallion semen before and after sorting and after freezing and thawing. Four ejaculates from each of two fertile stallions were collected 1 week apart and evaluated for percent total sperm motility (TM), percent viable acrosome-intact sperm (VAI), and DNA quality (percentage of DNA fragmentation index). Freezing caused, independently from CC and SLC treatments, a significant decrease of TM (P < 0.05) and VAI (...
Henry M, Amaral D, Tavares FF, Santos NR.The aim of the present study was to analyse the effect of hydrocoele of the vaginal cavity of stallions on semen characteristics, libido and fertility, and to contribute to the understanding of the aetiopathology of this condition in stallions. Hydrocoele did not substantially affect either the libido or semen characteristics of affected stallions compared with a control group, and had no effect on fertility. However, the protein content of hydrocoelic fluid was significantly higher than that of peritoneal fluid and was lower than the protein content of blood serum. Electrophoretic profiles of...
Álvarez C, Luño V, González N, Gil L.Sperm quality in donkeys (Equus asinus) after freezing thawing is still considered lower than that from other animals, including horses. The aim of this study was to test a new freezing extender supplemented with jenny colostrum on donkey sperm. After thawing, we evaluated sperm motility by means of computer-assisted analysis, viability by SYBR-14 and propidium iodide (PI), membrane functional integrity by HOS-test and acrosome integrity by isothiocyanate conjugated with peanut agglutinin (FITC-PNA) and PI. Ejaculates were collected from five fertile Donkeys. Sperm samples were pooled, diluted...
Schulman ML, Marlow CH, Nurton JP.The data and an analysis of the statistical summaries from the 'Return of Mares' of the General Stud Book of The Jockey Club of Southern Africa from 1975-1999 are presented. The total number of mares covered per season ranged from 7393 (1992) to 5180 (1995). The total living produce in the period surveyed was 95 317 foals. The categories of data examined include: the total number of mares covered per season; the total numbers and percentage of their living produce; the total numbers and percentage dead produce, 'slips' and foals born dead, barren and 'no return' mares; and the total number of ...
Raz T, Gray A, Hunter B, Card C.Superovulatory treatment may potentially increase the embryo recovery rate and the per-cycle pregnancy rate in normal or subfertile mares that are managed properly. However, some studies suggest a possible negative effect of superovulatory treatment on ovarian follicular maturation and embryo viability. Objectives of the present study were to investigate the early effects of eFSH treatment in reproductively normal mares in terms of: folliculogenesis, pregnancy rate, early embryonic development, reproductive tract parameters (tone and edema), and serum estradiol-17beta and progesterone concentr...
Hinrichs K.In vitro embryo production is not yet successful in the horse, largely due to low rates of fertilization in vitro. However, methods to produce embryos from isolated oocytes have been developed. Oocytes may be recovered from living mares by aspiration of the dominant preovulatory follicle by trans-abdominal puncture, and from both preovulatory and immature follicles by trans-vaginal ultrasound-guided puncture. Transfer of in vivo-matured oocytes to the oviducts of bred recipient mares has resulted in good pregnancy rates (75-85%). Little work has been done on transfer of horse oocytes matured i...
Casey PJ, Robertson KR, Liu IK, Espinoza SB, Drobnis EZ.Subfertility in stallions is common, and methodologies are needed to increase the fertility in these animals. In other species, removal of the dead sperm from semen increases the quality and fertility of semen. With horse semen we evaluated 48 combinations of column separation techniques using micro-spin chromatography columns. The greatest improvement in motility was observed with glass wool, whereas glass beads exhibited the greatest recovery of motile sperm. Although centrifugation time did not influence recovery rate or percent motility, a column length of 2 cm was superior for recovery of...
Ginther OJ.Examples of research discoveries and first reports on mare reproduction by the O.J. Ginther team are (1) determined daily circulating concentrations of four hormones during the estrous cycle, (2) showed that mares can be induced to ovulate and superovulate by hormone treatment during both ovulatory and anovulatory seasons, (3) demonstrated that prostaglandin F2α was the luteolysin in mares, (4) described the mare's elaborate hormonal and biochemical mechanism for selecting the ovulatory follicle from a pool of like follicles, (5) developed the method for diagnosing fetal sex by Day 60 using l...
Sieme H, Bonk A, Hamann H, Klug E, Katila T.The effects of different artificial insemination (AI) techniques and sperm doses on pregnancy rates of normal Hanoverian breed mares and mares with a history of barrenness or pregnancy failure using fresh or frozen-thawed sperm were investigated. The material included 187 normal mares (148 foaling and 39 young maiden mares) and 85 problem mares with abnormal reproductive history. Mares were randomly allotted into groups with respect to AI technique (routine AI into the uterine body, transrectally controlled deep intracornual AI ipsilateral to the preovulatory follicle, or hysteroscopic AI onto...
Pascoe DR, Stover SM.A surgical technique for removal of one conceptus from mares with twin concepti more than 35 days of gestational age was evaluated. One conceptus was removed surgically from each of 15 mares carrying twin concepti that were 41 to 65 days of gestational age. As determined by ultrasonography, eight mares had bicornuate and seven mares had unicornuate twin concepti. For maintenance of pregnancy if surgical trauma should cause prostaglandin release and luteolysis, progesterone was administered prophylactically. Flunixin meglumine was administered perioperatively to minimize prostaglandin release. ...
Pye J, Clulow J, Adkins A.To describe the laparoscopic transection of restrictive bands of the mesosalpinx as a useful adjunct to the topical application of prostaglandin E to treat mares with suspected uterine tubal blockage. Methods: A standard left flank laparoscopic approach was made to the abdomen using three laparoscopic portals. If restrictive bands of the mesosalpinx were observed traversing the uterine tube perpendicularly, they were carefully transected and 1 mg of prostaglandin E was then applied to the external surface of the uterine tube. Skin incisions were closed with surgical staples and the procedure...
Chiba A, Ujiie Y, Aoki T.While intrauterine fluid (IUF) is observed as mucous in healthy mares during estrus, the presence of IUF during diestrus is an indicator of endometritis. Mating induces endometrial inflammation in healthy mares, called mating-induced endometritis, that disappears within 1-2 days after mating. On the other hand, it is also known that IUF remaining beyond 12 hr after mating can cause persistent inflammation, bacterial growth, and decreased fertility. This study aimed to investigate the relationship between the presence of IUF and cervical bacteria before and after mating. Mares were classified i...
Reilas T, Huhtinen M, Oksanen M, Katila T.The aim of the study was to determine whether neutrophil numbers (PMN), trypsin-inhibitor capacity (TIC), lysozyme, N-acetyl-beta-D-glucosaminidase (NAGase), beta-glucuronidase (B-Gase), total protein, and plasmin in uterine lavage fluid of postpartum (p.p.) mares, either at the time of foal heat insemination or around the time of arrival of the embryo in the uterus, could be used in predicting conception. Fifteen mares were inseminated within 13 h after the first p.p. ovulation. Uterine lavage fluids were successfully collected from 9 out of 12 mares before insemination and from all 15 mares ...
